Efforts for preservation of food products go back many years. Perhaps one of the earliest methods for preserving food products was the drying of vegetable products. Many vegetable products naturally dried during the life cycle of the plants normal life, e.g., beans that dry on the plant. The beans and grains were stored for use during the winter season when the plants went through their dormant period. Later man learned the art of the smoking of meat products and the like as well as many other preservation methods.
As food science began to develop, man learned that certain food products were superior if they were maintained at a desired moisture content. Food products such as cheeses and meat jerky were preferably maintained at a particular moisture content.
It is well recognized that during cold weather, particularly in the Northern climes, the indoor moisture content may often be very low. This low humidity causes damage, for example the drying out of foods resulting in the ruination of the foods. The foods would become dried out which destroys the flavor of the foods. Some foods such as dried fruits become hard and lose desired succulent texture. This in turn reduces the enjoyment of the foods. Dry cheeses such as block Parmesan need to maintain a moisture content of about 26 to 32% and a water activity of 0.84. Slightly more moist cheeses such as Cheddar, Emmental or Gouda have moisture ranges of 30 to 38% water with water activity (AW) of approximately 0.95. Cheeses desirably are aged to develop flavor. Dried meat products such as jerky (28-34% water, Aw=0.75 to 0.80) or “hard” sausages (cervelat, or hard summer sausage 38-45% water, Aw 0.85) are also widely manufactured and distributed. The moisture content needs to be maintained in the desired range throughout the aging and the subsequent storage until consumed.
Since many molds grow readily at Aw greater than 0.85 and some grow significantly at Aw of 0.75, such meat and cheese products are commonly spoiled by surface mold growth. Since it is desirable to have as much water in the product to maintain a pleasing texture yet control the amount of mold growth, it is important to maintain the Aw of such products in a narrow range just lower than the Aw at which rapid mold growth occurs. Alternately, the growth of mold can be prevented by a very low oxygen environment or inhibited by compounds such as benzoic acid, sorbic acid, propionic acid, or other mold inhibitors. Such compounds are usually incorporated into the product or during manufacture, or deposited on the surface of the product by processes such as smoking.
Over the years, sophistication has developed in humidity control devices. Homes today often include a humidifier that is associated with the central furnace or heating system. Water is automatically fed into the humidifier. The water is exposed to warm moving air which picks up the moisture, carrying the water vapor throughout the home. Electronically controlled humidity regulators are very effective, but expensive and not very portable.
Desiccants have been used to completely or almost completely remove all the humidity in the air. Desiccants typically leave the humidity at or quite near 0%, or at levels lower than is acceptable in certain food environments.
In other instances environments may contain an excess amount of water vapor. Such a condition is typically confronted in the below ground level portion of the house, typically referred to as a basement. If the basement is located in a soil environment that contains high moisture, the moisture may move through the walls, e.g., concrete, of the basement raising the moisture content in the basement air to an unacceptably high level. High humidity occurs in many geographical locations such as the Pacific Northwest or the Gulf Coast in the United States. Unless well designed and operated storage spaces are used, products held for sale in such areas are subject to humidity high enough to allow mold growth.
Devices have been designed to lower the moisture content. Such devices are commonly referred to as dehumidifiers. These devices often work on a principle of refrigeration. The devices include a tubular coil through which a compressible fluid is passed. When the fluid is permitted to expand, the fluid rapidly lowers the temperature of the tubing. As moist air is passed over the tubing, condensation takes place on the tubing forming water which drops down into a removable pan. Periodically the pan is removed and emptied. All too often, the dehumidifier is forgotten, the pan overflows onto the floor and the water then evaporates, again raising the humidity.
Humidifying devices and dehumidifying devices of the type just described are generally not suitable for use in a package or case containing foods. The described humidifying devices and dehumidifying devices take up a substantial amount of space and simply will not fit within a small area. Attempts have been made to design small devices that fit within a small area.
Humidors today are available from tobacco shops for use with cigars. Such devices typically are glass and wood cases of sizes which typically are not portable. These devices may be anywhere from 12 inches by 12 inches by 5 inches or larger. Some humidors are large enough for several people to walk into simultaneously. The prior food cases which are humidified often use a sponge or a tube filed with water.
While such devices are commonly found today, these devices have inherent problems. For example, the humidifying cases may not be portable. The cases may be heavy and difficult to move. When an individual decides to take a vacation or would like to carry a few foods with him over a long period of time, these foods will become distasteful because the current devices are not portable. The prior humidifying cases generally have no control of the level of humidity. Prior devices are only designed to add water to the food environment. Some existing humidifying cases have problems with off flavors. Other existing humidifying cases tend to dry out the foods while others may get liquid water on the foods and result in molding.
One of the most serious problems with such storage of food products is the oxidation that takes place when the moisture content is at an undesirable level. Oxidation results in a rancid flavor in the food product, e.g., cheese or jerky.
One is confronted with two alternatives. One may leave the foods without a humidifying device and risk the foods drying out to such an extent that the foods lose all enjoyable flavors. Alternatively, one may place foods in a prior art humidifying case, of the type described, in which the case the foods will remain moist as long as they are consumed shortly after they are removed from the humidifying case. If the foods are not consumed shortly after being removed from the humidifying case, they may become distasteful because of oxidation. A financial loss as well as the loss of enjoyment may ensue from the loss of flavor of the foods.